This invention relates to elevators and, more particularly, elevators for separating and distributing whole freshly-harvested tobacco leaves.
Tobacco leaves are usually harvested using tobacco harvesting machines, or combines. Typically, the whole freshly-harvested tobacco leaves are transported in a container from the harvesting machine in the field to a transfer facility where the tobacco leaves are transferred to tobacco curing bins. The tobacco curing bins are subsequently placed in curing barns, where the tobacco leaves are bulk cured. A typical tobacco curing bin is disclosed in U.S. Pat. No. 4,520,579 (De Cloet et al.).
The whole tobacco leaves should be open and flat when they are placed in the tobacco curing bin. In particular, the surfaces of the tobacco leaves should generally be parallel, and the leaves should be uniformly distributed in the curing bin. This uniform distribution permits effective bulk curing of the tobacco leaves. If the tobacco leaves are uniformly packed in the curing bin, then the heating and conditioned air which is forced between the leaves during bulk curing in the curing barn will flow uniformly through the curing bin. However, if the tobacco leaves are not uniformly packed in the curing bin, and voids remain between tobacco leaves, then the heated and conditioned air will tend to flow through the voids. The result of the heated and conditioned air flowing through voids is that some of the tobacco leaves will not be exposed to the heated and conditioned air to the extent necessary for proper curing.
Immediately after harvesting by a harvesting machine, the tobacco leaves typically are placed in a receptacle on a machine in a disordered and non-uniform mass. Also, leaves at the bottom of the receptacle on the harvesting machine tend to become compacted into clumps due to the weight of tobacco leaves pressing on the leaves at the bottom. In addition, the moisture content of the leaves fluctuates, largely depending on conditions at harvesting. The tobacco leaves which have higher moisture content have a greater tendency to agglomerate into clumps.
As noted above, it is desirable that the tobacco leaves are distributed substantially uniformly in the curing bin, with the tobacco leaves open and substantially parallel to each other. However, the result of mechanical harvesting is to provide a disordered and non-uniform mass of tobacco leaves in the receptacle at the harvesting machine, some of which may be agglomerated into clumps. The tobacco farmer therefore is confronted with the problem of how to achieve a substantially uniform distribution of leaves in the tobacco curing bin when the tobacco leaves are provided in the receptacle of the harvesting machine in a disordered and non-uniform mass. Also, traditional separation and distribution methods have often relied at least partly on manual labour, but tobacco farmers are required to use machines as much as possible due to increases in labour costs over the long term.
Various devices are known which are intended to result in a uniform distribution of tobacco leaves in the tobacco curing bin. For example, in U.S. Pat. No. 6,321,758 B1 (Sturgill et al.), a tobacco transferring system is disclosed in which, after the tobacco leaves have been transported in crates to a transfer facility, the tobacco leaves are subsequently dumped onto conveyors. The conveyors, which are arranged in pairs in series (i.e. end to end) and operated at different speeds, move the tobacco leaves to curing bins.
U.S. Pat. No. 4,530,203 (De Cloet) discloses a tobacco harvester discharge system which is intended to be positioned on the tobacco harvesting machine, to put the tobacco leaves in a curing bin positioned on the harvesting machine. Harvested tobacco leaves are sent through rolls positioned at the end of a conveyor, which launch the leaves into an airborne trajectory into the curing bin. After the leaves have been launched, they are supported by air blown upwardly from a fan positioned underneath the leaves, so that the tobacco leaves will float along a predetermined trajectory into the curing bin.
For various reasons, the known devices for distributing whole freshly-harvested tobacco leaves in tobacco curing bins are deficient. There is therefore a need for a conveyor for separating and distributing whole freshly-harvested tobacco leaves.
In abroad aspect of the present invention, there is provided an elevator for separating and distributing a load of whole freshly harvested tobacco leaves. The load includes a number of clumps of agglomerated tobacco leaves. The elevator has an inclined frame extending between a lower end and an upper end, an endless conveyor, and a declumper. Also, the frame carries deck portions extending substantially between the lower end and the upper end, and the conveyor is adapted to travel over the deck portions in an upward direction and under the deck portions in a downward direction. The endless conveyor is also adapted to carry the tobacco leaves to the upper end and discharge the tobacco leaves therefrom. In addition, the declumper is attached to the frame and positioned above the conveyor, and is adapted to buffet the clumps of tobacco leaves to separate the whole tobacco leaves in the clumps from each other. The declumper includes a rotatable declumper axle positioned transversely to the conveyor and nose elements projecting radially outwardly from the declumper axle. Each nose element includes a blunt end distal to the declumper axle and adapted to push the tobacco leaves apart without puncturing the tobacco leaves. Accordingly, the conveyor is adapted to elevate the load to the upper end so that the elevated load may fall from the upper end and the tobacco leaves may separate from each other.
In another aspect of the present invention, the elevator includes the inclined frame, the endless conveyor, and a distribution mechanism. The distribution mechanism is adapted to distribute the discharged tobacco leaves in a tobacco curing bin positioned substantially underneath the upper end of the frame. The distribution mechanism includes a main panel having a top end and a bottom end, and the top end is coupled to the frame by a hinge spaced a distance from the upper end of the frame which is selected to permit the discharged tobacco leaves to fall a predetermined distance between the frame and the panel, to maximize separation of the tobacco leaves from each other. In addition, the main panel is adapted to oscillate on the hinge relative to the frame, for distributing the tobacco leaves uniformly in the bin to optimize curing. As a result, the tobacco leaves discharged from the upper end of the frame are distributed evenly across the bin.